My 72 Year Old Sister Started Having Dizziness About 7

My 72 year old sister started having dizziness about 7 hours ago, no N/V, no fever no pain. She has to stay in one position- she is eating crackers and PB and hydrating. BP 132/85, P80, Regular. Nothing but this. No signs of a stroke, me ration normal-'very sharp. Moshe lives with us. Amy idea on a sudden onset like this? No earache, no vision alterations...thank you